ARC Objective-C中的C风格多维数组

I'm trying to implement an n x n multidimensional array of ints in Objective-C, and because using NSMutableArray seems to be too much of an overhead I decided to implement it using only C's malloc and free. My question is, is the code below correct (no memory leaks) under ARC Objective-C?

我正在尝试在Objective-C中实现一个n x n多维数组的int,因为使用NSMutableArray似乎是一个太大的开销我决定只使用C的malloc和free来实现它。我的问题是,ARC Objective-C下的代码是否正确(没有内存泄漏)?

@interface TwoDimensionalArray
{
    int **array;
    int size;
}
@end

@implementation TwoDimensionalArray
- (id)initWithSize: (int)s
{
    if(self = [super init])
    {
        size = s;
        array = malloc(sizeof(int*) * size);
        for(int i = 0; i < size; i++)
        {
            array[i] = malloc(sizeof(int) * size);
            for (int j = 0; j < size; j++)
            {
                array[i][j] = 0;
            }
        }
    }
    return self
}
- (id)init
{
    return [self initWithSize:1];
}
- (void)dealloc
{
    for(int i = 0; i < size; i++)
    {
        free(array[i]);
        array[i] = nil;
    }
    free(array);
    array = nil;
}
@end

If this is not correct, or if you think there is a definitely better way to do it in Objective-C without doing mallocs, please tell me. Thanks.

如果这不正确,或者你认为在没有做mallocs的情况下在Objective-C中有更好的方法,请告诉我。谢谢。

1 个解决方案

#1

ARC implements automatic memory management for Objective-C objects and blocks, but does not automate malloc/free. (References: Clang/ARC documentation: General, ARC Release Notes: FAQ.)

ARC为Objective-C对象和块实现自动内存管理,但不自动化malloc / free。 (参考文献:Clang / ARC文档:General,ARC发行说明:FAQ。)

So your question is unrelated to ARC: Everything you malloc() must be free()'d (and dealloc is good place to do so). From the first look your code looks OK.

所以你的问题与ARC无关:你malloc()的所有内容都必须是free()'d(并且dealloc是这样做的好地方)。从第一眼看,您的代码看起来没问题。

(Small remarks: Zeroing the array pointers in dealloc is not necessary, but NULL would be the appropriate pointer value to assign, nil is meant for Objective-C objects.)

(小备注:无需在dealloc中清零数组指针,但NULL将是要分配的适当指针值,nil用于Objective-C对象。)

I do not know how much overhead using Objective-C collections such as NSMutableArray would cause, that should be tested (as already said in the comments) by profiling.

我不知道使用诸如NSMutableArray之类的Objective-C集合会产生多少开销,应该通过分析来测试(如评论中已经说过的)。